Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9795846 | Materials Science and Engineering: A | 2005 | 7 Pages |
Abstract
In order to overcome the recrystallization embrittlement of molybdenum, internally nitrided dilute Mo-Ti alloy specimens having a heavily deformed surface microstructure were prepared by a novel three-step internal nitriding process at 1223-1873Â K in N2 gas. Grain growth behavior and mechanical properties of nitrided specimens were investigated. Primary nitriding of the present alloys below their recrystallization temperature induced a uniform dispersion of ultrafine Ti-nitride precipitates without causing recrystallization. After secondary and tertiary nitriding, those precipitates grew into rod-like particles with a diameter of about 20Â nm and a length of 50-120Â nm, maintaining their deformed microstructure due to the pinning effect on grain boundary migration. The depth of the region where the recrystallization of the molybdenum matrix was suppressed was greatly dependent on the secondary nitriding temperature. The recrystallization temperature of the specimen subjected to three-step nitriding was elevated above 1873Â K. The yield strength at 298Â K obtained from nitrided Mo-0.5Â wt% Ti alloy was about 1.6 times as high as that of the recrystallized specimen. Ductile-to-brittle transition temperature of nitrided Mo-0.5Â wt% Ti alloy was about 181Â K.
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
Masahiro Nagae, Yoshito Takemoto, Tetsuo Yoshio, Jun Takada, Yutaka Hiraoka,